The present invention relates to providing audio and/or video, and more particularly to a compact disc player.
Currently, digital video and audio is recorded on compact discs using compression technology created by the Moving Picture Experts Group (hereinafter referred to as xe2x80x9cMPEGxe2x80x9d). This working group was formed by the International Standards Organization and the International Electrotechnical Commission (hereinafter referred to as xe2x80x9cISO/IECxe2x80x9d) to ensure interoperability between different manufacturer""s CD players and the many titles from content producers. The resulting standard is officially known as ISO/IEC, Coded Representation of Picture, Audio and Multimedia/hypermedia Information, ISO 1172. More commonly known as MPEG-1. MPEG-1 focuses on the delivery of video within the constraints of the compact disc, {fraction (1/416)} megabits per second. By using MPEG-1 technology, a full motion image and audio that is about 74 minutes long can be stored on a 12 cm diameter compact disc. The MPEG-1 information stored on a video compact disc (hereinafter referred to as xe2x80x9cVCDxe2x80x9d) can then be decompressed to produce a video signal and audio signal on a VCD player.
As is understood by one of ordinary skill in the art, FIG. 1 displays standard components of a VCD player. Motor Drivers 130 are used to rotate the VCD 120 so that the MPEG-1 encoded information stored on the VCD can be accessed in order to produce audio and video on a display 1300.
An optical pickup 140 reads the MPEG-1 information off of the VCD 120. The Servo 150 controls the motor drivers 130, via line 115, to provide a constant stream of digital information 100 through line 101. A Digital signal processor (xe2x80x9cDSPxe2x80x9d) 160 receives the digital information 100 through line 103 and further processes the signal providing a digitally processed signal 104 to the MPEG audio/video decoder 190, through line 107. The MPEG audio/video decoder 190 decompresses the digitally processed signal 104, and produces an audio signal 102 and a video signal 106. The audio signal 102 is sent to the speaker 180a and/or the audio output ports 180b, through line 105. A video amplifier 1000 receives the video signal 106 from the MPEG audio/video decoder 190 via line 109. The video amplifier 1000 converts the video signal 106 and provides an analog signal 108 to the video signal processor 1200 through line 111. This analog signal 108 is converted into a digital display signal 110 which is provided to a display panel 1300 through line 113. A switching power supply 1100 provides power through line 119 to the video signal processor 1200. A backlight module 1400 is used to illuminate the display panel 1300 through line 117 to enable viewing of the information.
FIG. 2 illustrates an expanded view of 190, 1000, 1100, 1200, 1300 and 1400 and their interconnections as illustrated in FIG. 1. The MPEG audio/video decoder 190 provides a composite video bit stream 106a and a S-video bit stream 106b on lines 109a and 109b respectively. A video amplifier 1000 converts the signals provided from the MPEG audio/video processor 190 and provides an analog R signal, G signal, B signal, C synchronization signal, X synchronization signal, and Y synchronization signal on lines 111R, 111G, 111B, 111C, 111X, and 111Y. An AID converter 220, located within the video signal decoder 1200, receives the R signal, G signal, and B signal and produces a 6 bit data stream 202 which is sent to the control IC 230, through line 201. The control IC 230 receives the data stream 202, the C synchronization signal, X synchronization signal, and Y synchronization signal via lines 201, 111C, 111X, and 111Y respectively. The control IC 230 produces a Y driver control signal 204, a X driver control signal 206, and a data stream 208. These display signals are sent to the X driver 250a and Y driver 250b via lines 203, 205, and 207, respectively. A switching power supply 1100 provides a Vr on line 119a and a Vee on line 119b to a power supply circuit 240 contained within the video signal processor 1200. The power supply circuit provides the necessary power to the X driver 250a and the Y driver 250b, through lines 209, and 211, in order to power the corresponding pixels on the screen 260. The X driver 250a, the Y driver 250b and the screen 260 are all located on display panel 1300. A backlight module 1400 is used to provide illumination to the screen 260 to enable viewing of the information, through line 117.
There are a number of disadvantages with the current VCD player. First, the design is complex. In the current VCD player the digital decoded signal 106 from the MPEG audio/video decoder 190 cannot be sent directly to the display. Therefore the digital signal 106 must be further processed to an analog signal 111 which requires more power thereby limiting the amount of play time when using a DC power source. Second, the extra conversion and processing of the signal read from the VCD degrades picture/sound quality. Third, the large number of semiconductor devices necessary to operate the current VCD player add to the overall size of the device. Fourth, the connections between these extra semiconductor devices emits unwanted electromagnetic radiation which is regulated by the FCC and must be kept at a minimum. Fifth, the amount of power being used by the backlight which will reduce the play life of the device when using DC power is not controlled. Sixth, current VCD players do not have a way of decoding VCD""s which are copy protected. Seventh, the cost of the current VCD player is high due to the large number of semiconductor devices and expensive components.
Therefore, it is desirable to produce a VCD player which solves the above disadvantages and to present an inexpensive VCD player that enables extended battery life and produces a minimum of electromagnetic radiation. Also, a VCD player which also plays either audio CD""s or decodes copy protected VCD""s is desirable.
An embodiment of the present invention provides an apparatus capable of playing either audio compact discs or VCD""s. Furthermore the apparatus has been configured to minimize the amount of semiconductor devices used and the distance between them, thereby making the apparatus portable, inexpensive and extending the life of the power supply.
An embodiment of the inventive apparatus includes a motor for rotating the compact disc, a digital read path for obtaining a digital signal from the compact disc and a display device for outputting the video portion of the digital signal. The digital read path includes, among other things, an optical pickup for obtaining a readout signal from the compact disc, a system control for determining whether the readout signal supplied from the optical pickup contains MPEG-1 audio/video and for selecting the destination of the readout signal. A digital signal processor processes the readout signal supplied from the optical pickup and provides an audio signal and a video signal. A MPEG audio/video decoder processes the video signal supplied from the digital signal processor. A digital control circuit is coupled to the MPEG audio/video decoder and supplies a digital signal to the display. A backlight module is connected to the display for controlling the amount of power sent to the display.
The inventive apparatus thus provides a reduced number of semiconductor devices to perform the desired result of displaying a full motion picture onto a display screen. This reduction in the number of semiconductor devices reduces the overall size of the apparatus and limits the amount of connections between devices. Reducing the amount of connections between semiconductor devices limits the amount of unwanted electromagnetic radiation, which must be kept at a minimum as required by the Federal Communications Commission (xe2x80x9cFCCxe2x80x9d). Not only does the reduction in the number of devices reduce the overall size and limit unwanted radiation it further improves the quality and desirability of the operation of the device by both limiting the amount of power needed to drive the device and improving the quality of the audio/video signal. By using a smaller number of semiconductor devices to process the signal you further limit the unwanted introduction of white noise that is generated during signal modification and amplification. By limiting the noise you can produce a more accurate and clearer audio/video signal.
The power to the device is conserved in at least three ways. First, the power needed to drive the device is reduced due to the reduction of the semiconductor devices used to process the signal. Secondly, the power is conserved by the use of the backlight sensor. The backlight sensor detects whether the apparatus is using AC or DC power. If the device is using DC power the backlight sensor will limit the amount of power that is provided to the display to approximately ⅔ of the maximum output. This reduction in backlight will have a minimal effect on the display quality and conserve battery life. Power is also conserved by the use of a sensor which monitors power source and disables the DC power (batteries) when AC power is available. By selecting the AC power over DC this conserves battery life by only drawing DC power when necessary.